Electric heating device.



F. C. E. BURNETT & E. J. BRUNNING'.

ELECTRIC HEATING DEVICE.

APPLICATION FILED NOV. 27, I916.

1,234,280. Patented July 24, 1917.

2 SHEET SSHEET 1.

Alma; 117mm REL-EUR E77- W E. IJHBRUIINIHE.

F. C. E. BURNETT & E. J. BRUNNING.

ELECTRIC HEATING DEVICE.

APPLICATION FILED NOV. 2?. 1916.

Patented July 24, 1917.

2 SHEETS-SHEET 2 Jiumms 55'. 5.312775 77,- E JHFIY HIV/NE:

U/T/VEFE UNITED STATES PATENT OFFICE.

I'BAIGIS BURNETT AND ERNEST JOHN IBBUNNIRG, 0F MONTREAL, QUEBEC, CANADA.

Speculation of Letters Itatcnt.

ELECTRIC nnarnsre DEVICE.

Patented July 24, 1917.

Application filed Iovenibcr 87, 1916. Serial No. 133,898.

To allwbomitmayconcem;

Be it known that we, FRANCIS C Enwm 13mm and ElmmrJolm BRUN- Nmc, bothsubjects of the King of Great Britain, and residents of the city ofMongaging the of the gun. It is obvious,

however, that the method here described is applicable to the heatingof-any complete circuit of metal for the tempering or annealing or otherp It has already been proposed to heat metallic rings in a device inwhich the rings constitute the secondary circuits of a transformer. Theobjects of the present invention are to provide improvements in thisapparatus, to secure more satisfactory and accurate operation thereofunder commercial conditions, and to make such improvements in theelectrical connection which will enable the various circuits to beregulated to suit conditions. The invention comprises the improvedconstruction and arrangement of parts hereinafter described in detail inthe accompanying specification and drawlugs- In the drawings: Figure 1is a sectional elevation through an embodiment of the invention.

Fig. 2 is a cross section on the line 2-2, 1

Fig 3 is aside elevation with the refractory chamber for the ring to beheated removed, and having the wiring indicated diae r- Fig. 4 showsdiagrammatically the electrical connection by which thefvoltage is Fig.5 shows diagrammatically the method employed to control the primaryelectric circuit.

In the drawings like characters of reference refer to correspondingparts in each ferring to the A represents a magnetic core or circuitconveniently built up of suitable plates of iron or steel, and in theembodiment illustrated, being of rectangular form. A portion B, in thiscase the top portion of the core, adapted to be raised and lowered bysuitable means such as the lever C which is shown pivoted to a supportD.

E represents a primary winding mounted on one side of the magnetic coreand consisting of a suitable number of turns in a conductor wound in theusual way, current beiigl1 supplied from the conductors 10 an It isimportant to insure that the circuitthrough the primary winding shouldnot be completed until the movable part of the is movable and is core 1sin exact position, as otherwise the back E. M. F. in the primary windingwould not be great enough and the current would be too high.

To perform this function, I provide a contact 12-on the lever C adaptedto cooperate with a suitable fixed and adjustable contact 13 on thesupport 14, the conductor 10 being connected to the contact 12 and aconductor 15 leading from the contact 12, the conductor 11 and conductor15 being connected to the double pole switch 16 which 1s suitablyconnected to a source of electric power.

The movable to the other part of the magnetic core, but small air gaps20 and 21 may be left between and a further regulation in the amount ofheating may be made by adjusting the amount of this air gap through theadjustment of the fixed contact 13 in any convenient way.

It will be observed that the reluctance of the magnetic circuit may bealternated at will to suit the needs of the case by varying the air gaps20 and 21, or inserting pieces of non-magnetic material in these airgaps.

Surrounding the prima winding E, is a casing C of suitable re actorymaterial adapted to contain the ring to be heated. This case is annularin form and serves the double purpose of minimizing the loss of heatfromthe material to be heated and protecting the primary winding and themagnetic core from injury, due to the heat radiated or conducted fromthe material to be heated.

, H represents the ring to be heated and part B need not exactly fitwhich is located in the chamber G and will constitute the secondarcircult. The top or cover 24 of the re actory chamber 1s connected bysuitable brackets 25 to the movable part B andis adapted to movetherewith.

In operation the lever C is raised, carrym the part B and cover 24. Themetal rlng to be heated is then placed in the chamber G and the switch16 thrown into operative position and the lever 0 brought down. As soonas the contacts 12 and 13 meet the circuit will be completed through theprimary winding E which will induce a heavy current in the article Hwhich forms 'the secondary in which heat may be maintained as long asthe current is on. When the heating is completed, the switch 16 may beopened and the lifting of the part B Wlll carry the cover 24, permittingthe removal of the heated article.

Under certain conditions it may be desirable to vary the voltage in thearrangement above described and the preferred manner of doing this isshown in Fig. 4;, in which E represents the primary winding in Fig. 1.10 and 11" indicate connections from the winding E to a double poleswitch 16. K represents auto-transformer having a winding 30 on amagnetic core 31, the construction and operation of which is well knownin,the art and this transformer is in the circuit between the primarywinding E and the switch 16.

If it is desirable to regulate the primary circuit by non-inductivemeans, it may be done as shown in Fig. 5, in which E mdicates theprimary winding, 10 and 11 connections between it and a double poleswitch 16, any one of which connections, such as 11 a non-inductiveresistance 22 is inserted in series with the wire 11.

As many changes could be made in the above construction and manyapparently widely different embodiments of our invention, within thescope of the claims, constructed without departing from the spirit orscope thereof, it is intended that all matter contained in theaccompanying specifications and drawings may be interpreted asillustrative and not in a limiting sense.

What we claim as our invention is:

1. An electric heating device comprising in combination a rectangularmagnetic core having a movable top portion, means for raising andlowering the top portion, a primary winding mounted on one side of themagnetic core, an annular casing surrounding the primary winding adaptedto contain a ing on the core, an annular chamber adapted to contain thearticle to be heated and surrounding the primary winding.

3. An electric heating device comprising a magnetic core having amovable part, a primary winding, a secondary winding formed by anarticle to be heated, and means preventing the completion of the currentthrough the primary winding until the movable part of the magnetic coreis in proper relative position to the other part.

4:- An electric heating device comprising a magnetic core having amovable part, a primary winding, a secondary winding formed by anarticle to be heated, and means preventing the completion of the currentthrough the primary winding until the movable part of the magnetic coreis in proper relative position to the other part, said means comprisinga fixed contact and a movable contact moving with the movable part.

In witness whereof we have hereunto set our hands in the presence of twowitnesses.

